The present invention relates to a positive type radiation-sensitive resin composition and, particularly, to a positive type radiation-sensitive resin composition suitable as a chemically-amplified resist useful for microfabrication utilizing various types of radiation, for example, deep ultraviolet rays such as a KrF excimer laser or ArF excimer laser, X-rays such as synchrotron radiation, or charged particle rays such as electron beams.
In the field of microfabrication represented by fabrication of integrated circuit devices, lithographic technology enabling microfabrication with a line width level of 0.20 μm or less has been demanded in recent years in order to achieve a higher degree of integration.
A conventional lithographic process utilizes near ultraviolet rays such as an i-line radiation. It is known in the art that microfabrication with a line width of a sub-quarter micron order using near ultraviolet rays is very difficult.
Use of radiation with a shorter wavelength has been studied for enabling microfabrication with a line width level of 0.20 μm or less. As the radiation with a shorter wavelength, deep ultraviolet rays such as a bright line spectrum of a mercury lamp and an excimer laser, X-rays, an electron beams, and the like can be given, for example. Of these, a KrF excimer laser (wavelength: 248 nm), an ArF excimer laser (wavelength: 193 nm), an F2 excimer laser (wavelength: 157 nm), and the like are gaining attention. As a radiation-sensitive resin composition applicable to irradiation (hereinafter called “exposure”) by the excimer laser, a number of chemically-amplified radiation-sensitive resin compositions utilizing a chemical amplification effect brought about by a component having an acid-labile functional group and a photoacid generator which generates an acid upon exposure have been proposed.
The chemically-amplified radiation-sensitive resin composition utilizes the effect of the resin being insoluble or scarcely soluble in alkali by itself, but becoming alkali-soluble by the action of an acid, and the resin to dissociate an acid-labile group in the copolymer by the action of an acid generated from the photoacid generator upon exposure to form an acidic group such as a carboxyl group or a phenolic hydroxyl group, which renders an exposed area on a resist film readily soluble in an alkaline developer.
Along with a rapid miniaturization trend of photolithography process, limit of resolution is close to less than half the light wavelength in the recent KrF photolithography process. Characteristics demanded for a positive type radiation-sensitive resin composition as a photo resist are becoming severer, especially increase in process margin is demanded.
Photoacid generators introducing a fluorine atom into a cation part of molecules are disclosed for increasing resolution of KrF excimer laser resist and EB resist (JP-B-3215562, JP-A-2001-75283 and JP-B-3082892).
Further, as a radiation sensitive resin composition excelling in a process margin particularly for KrF excimer laser, a radiation sensitive resin composition using a mixed photoacid generator comprising a photoacid generator having substituted group containing fluorine atoms and a predetermined photoacid generator is disclosed (JP-A-2004-219963).
However, to achieve a higher degree of integration in the field of semiconductor, focal depth allowance, resolution and pattern profile remain insufficient if only the photoacid generator which a fluorine atom introduced into a cation part is used. In addition, even if a mixed photoacid generator is used, the photoacid generator other such as sulfonamide results in pattern collapse depending on the photoacid generator.
Further, it is difficult to adjustment for the fabrication of semiconductor devices which are expected to become more miniaturized.